All these states control the water that reaches Egypt whose
large and rapidly growing population depends on the Nile for
irrigation and all other purposes.

Problems

The Nile basin contains two kinds of states: Those which have
rain and thus contribute water; those which have no rain and
which use the water.

The river drains the East African highlands from Ethiopia,
Kenya, Uganda, Burundi and Tanzania. But some of these countries themselves
have arid zones and want to use the water to irrigate them. A
possible crisis has been provoked by Tanzania's wish to build
a pipeline to some of its arid areas in central Tanzania. According
to the 1929 agreement no abstraction should occur without the
agreement of the lower states.

In February 2006 it is being reported that the level of Lake
Victoria is lower than it has been for many years. Uganda is
being blamed for letting too much water through the hydroelectric
dam it controls, contrary to an agreement with the other states
bordering the lake - Kenya and Tanzania. BBC
Report

There has been a serious drought in the whole area that feeds
into the lake. But the 2007 season has seen floods in the Sahel.

Egyptians may legitimately fear that if upstream countries
make use of the water the amount they receive could decline.
Elsewhere in the world is the example of the Yellow River in
China. Frequently in the dry season in recent decades no water
has reached the sea because so much has been abstracted. Such
an outcome would destroy Egypt as an economy and society. Another
example is the Colorado River in the western United States. By
the time it reaches the sea through Mexico it carries a big load
of salt and chemicals after much of its water has been diverted
to the cities of southern California.